<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>{% block title %}{% endblock %}</title>
    {% block head %}{% endblock %}
</head>
<body>
    <ul>
        <li>
            <a href="/">首页</a>
        </li>
        <li>
            <a href="/control">控制页面</a>
        </li>
        <li>
            <a href="/about">关于我们</a>
        </li>
    </ul>
{% block body %}{% endblock %}
<footer style="background-color: #ccc">我是底部的导航条</footer>
</body>
</html>